<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>canvas</title>
    <style>
        #game {
            background-color: #333;
        }
    </style>
</head>
<body>
<header>
    <h1>Drawing in Canvas</h1>
</header>
<canvas id="game" width="768" height="400">
    滚
</canvas>
<script src="../bower_components/jq/dist/jquery.min.js"></script>
<script>
    $(function () {
        let canvas = document.getElementById('game')
        let ctx = canvas.getContext('2d')
        ctx.fillStyle = 'rgba(200,200,100,.6)'
        ctx.beginPath()
        ctx.arc(100, 100, 50, 0, Math.PI * 2, true)
        ctx.closePath()
        ctx.fill()
    })

    // arc(x,y,radius,startAngle,endAngle,counterclokwise)
</script>
</body>
</html>
